The effectiveness of tailored online campaigning: Evidence from a field experiment targeting women

EPSA 2025, Madrid

Frederik
Thieme
frederik.thieme@hu-berlin.de

Humboldt-Universität zu Berlin

Heike
Klüver

Humboldt-Universität zu Berlin

June 26, 2025

Motivation 📢

Source: Opinion in The Scientific American (February 21, 2024)

Overview

  • ❓ Question: How effective is tailored online political advertising in mobilizing voters?
  • 💡 Argument:
    • conventional wisdom deems micro-targeting highly persuasive
    • appeals to salient group-identities should increase effectiveness
  • ️⚙️ Data & Method:
    • field experiment targeting women with German Green party, European Elections 2024
    • randomizing tailored vs. generic ads at ZIP-code level
    • 686,000 women reached, additional post-election survey (N = 950)
  • 📊 Results:
    • no effects on turnout or party vote choice in aggregate & survey analysis
    • low exposure and recall in the target audience

Targeting and tailoring political ads 🎯

Previous literature 📚

  • almost no evidence on tailoring effectiveness, yet
  • gender-based appeals frequent, but need causal tests from the field

Field Experiment

  • cooperation with the German Greens
  • targeting women (age 30-60) in the European Elections 2024
  • Facebook/Instagram ads randomized in 248 ZIP-codes
  • post-election survey with random selection from both treatment & control

Treatment

Treatment Ad

Control Ad

Data & Estimation ⚙️

  • official election results by the state’s returning officers
  • on-platform performance data
  • own post-election survey (N = 950)
  • aggregate analysis
    • city states: geospatial match of ZIP-codes with electoral districts (N=204)
    • territorial states: uniquely identified municipalities (N=273)
  • survey analysis

Results: Aggregate 📊

City States (Berlin, Hamburg, Bremen)

Results: Aggregate 📊

Territorial States

Results: Survey 📊

Limiting factors 📊

Limiting factors 📊

Takeaway 🥡

  • no effect of tailored ads in aggregate or survey analysis
  • although triggering salient group identities (gender, parenthood)
  • challenges the conventional wisdom on the persuasive power of micro-targeting (in politics)

Outlook 🔭

  • re-assessment of theoretical and strategic assumptions on tailoring
  • strategy-effectiveness appears to remain highly context-dependent

Thank you for your attention.

Questions or feedback? Hit me up:

Literature 📚

Cindy D. Kam, Cindy D. Kam, Allison M N Archer, Allison M. N. Archer, Allison M. N. Archer, Allison M N Archer, John G. Geer, and John Gray Geer. 2017. “Courting the Women’s Vote: The Emotional, Cognitive, and Persuasive Effects of Gender-Based Appeals in Campaign Advertisements.” Political Behavior 39 (1): 51–75. https://doi.org/10.1007/s11109-016-9347-7.
Erfort, Cornelius. 2024. “Targeting Voters Online: How Parties’ Campaigns Differ.” Electoral Studies 92 (December): 102872. https://doi.org/10.1016/j.electstud.2024.102872.
———. 2025. “Gendered Targeting: Do Parties Tailor Their Campaign Ads to Women?” The Journal of Politics, April, 736027. https://doi.org/10.1086/736027.
Haenschen, Katherine, and Jay Jennings. 2019. “Mobilizing Millennial Voters with Targeted Internet Advertisements: A Field Experiment.” Political Communication 36 (3): 357–75. https://doi.org/10.1080/10584609.2018.1548530.
Hewitt, Luke, David Broockman, Alexander Coppock, Ben M. Tappin, James Slezak, Valerie Coffman, Nathaniel Lubin, and Mohammad Hamidian. 2024. “How Experiments Help Campaigns Persuade Voters: Evidence from a Large Archive of Campaigns’ Own Experiments.” American Political Science Review 118 (4): 2021–39. https://doi.org/10.1017/S0003055423001387.